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HomeTurbineAircraftHelicopterTurbine Helicopters › Stretched wren/predator
10-11-2005 12:33 AM  13 years agoPost 1
hayabusa

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Hi I have been modifying the wren predator lately and should be back in the air shortly I have stretched the predator slightly so the model can take 810mm blades and my boom is now 25mm that should make everything a little better when I am doing autos and hopefully improve the climb rate just like it was when I was using the 720mm rotor Tec’s they are good blades. On my last flight before the mod I noticed the main gear mating to the pinion gear was very lumpy I have stripped the clutch bell down to find that all four bearing are worn out so I will replace them with quality SKF bearings they haven’t done bad its flown about 11 months with an IC engine in, then 3months with the turbine fitted. Has anyone else converted there model to take bigger blades. The wren engine is performing like the first day I run it absolutely beautiful if you’re buying a turbine the MW54 is the business. The cyclic is very responsive with my 4ccpm using four JR 8511, I am still using the modified predator tail box without any problems and I am now using a TT swash plate which is beautifully made and is a quality upgrade its rather chilly where I live so my flying will be limited till the spring comes I don’t like flying with cold hands its not best cheers Steve

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10-11-2005 12:15 PM  13 years agoPost 2
Bell Bloke

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UK

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Hi there, Bell Bloke here, I too fancy a "Limo Stretch" version of my Predator. How much and where do I get the bits from? Also how often do you change your primary gear oil mine had only used 3-4ml after 6 hours so I guess 10 hour top-ups should be fine? How many hours were on your bearings? All the best and many thanks. Love the Wren/Pred combo, the Wren is an absolute gem, it's such a civilised form of power.

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10-11-2005 07:38 PM  13 years agoPost 3
coolice

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Northamptonshire, England

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Hey,

I will not be far behind you in this stretching adventure

Length is everything

Will be good to hear your progress.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-11-2005 08:55 PM  13 years agoPost 4
hayabusa

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uk

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Hi bell bloke the wren gearbox is just like the MW54 brilliant! I check my box (pardon the expression) every 10 flights the danger is you expect the same 15ml to just pour out but the nature of the hypoid 90 oil is that it stays inside so you could easily assume its low on oil then put to much oil in then blow the oil seal so a top up of 3-4ml sounds ok to me. Now I have done 20 flights and removed the gearbox lid to check the amount of oil, I syringed out 11ml of old oil so what you are doing is definitely ok it’s a breeze to removed the gearbox lid so I will replace the oil every 30 flights which is about every 5hrs and every 10th flight put 3-4ml in. I checked the gearbox bearings they where perfect which we expect from wren turbines there products are superb. The predator is very easy to work on so the above doesn’t take that long to do and it gives you a chance to inspect the model while it’s stripped down the 720mm rotortec blades that come in the kit are perfect for the wren/predator it fly’s beautiful on them, I broke my blades when the tail gearbox failed! But I have modified the tail box its fine now, the model has not been flown yet with the boom conversion but will be shortly weather permitting. The clutch bell bearings had done 6gallons of cool power and then 20, 10minute flights with the turbine fitted cheer’s Steve.

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10-12-2005 09:05 AM  13 years agoPost 5
NEIL2-UK

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UK - South East

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HAYABUSA... what about clutch failure
Hi Steve

You forgot the early clutch failure!!

What about all the frame mods to stiffen up the turbine frame conversion and stop the frame twisting. You are right about changing to better quality bearings also... as I've also just advised someone else to change to either German or Japanese quality bearings.

I think that Rob also found the HeliLeisure upgrade parts to give a considerable improvement on the Predator... and changes to frame stiffness allowed for better control in extreme manoeuvres.

Now the boom change is completed... are you ready for the 800mm blades?
Did you use Vario as supply for the boom tube, as suggested.
There are now longer booms available as standard from Century, and designed for the New Breed of Pred Gasser, which I am looking at as another turbine conversion for some scale use.

Now I'm back from holiday I'll be in from Thursday onwards.

NEIL
HeliLeisure TT Conversions

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10-12-2005 11:48 AM  13 years agoPost 6
hayabusa

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uk

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Hi Neil oh dear! I am having too many senior moments these days its amazing what you forget at my stage of life I bought the predator from heli leisure and after ½ gallon cool power 30% the clutch shoe broke I was flying it gently honest!! It was a bummer I was enjoying myself to, but was sent a new one under warranty from heli leisure and was flying the following weekend then the head rotator blade holder bearings failed they felt like some one had thrown a bucket of sand in them, but I assure you I wasn’t flying on the beach! But quality bearings cured that. Now it seams like I am knocking the predator but all helicopters have there problems and (so do the people flying them) whoops!! But as long as you have the support of the manufactures and the shops aiming towards us modellers we can all feel a little better with our purchases I will list what I am using on the predator shortly my model is approximately 18months old so its not doing bad cheers Steve

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10-14-2005 04:22 PM  13 years agoPost 7
rspblake

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London uk. coulsdon

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Hi Steve and Neil

Yes heli leisure, they offered considerable improvement and suggestion on the Predator.

Simple upgrades to swash and A frame thru to better tail drive to stop ripping themselves apart in flight (although Steve’s idea LOL)

Was told at Charmouth that century was going to make an extended boom available.

looking fwd to how you went about fitted and what you used Steve.

Did u send the bits Neil?

Rob

(gunnell_s) still owes me money! ... web evorc.com

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10-16-2005 12:26 AM  13 years agoPost 8
hayabusa

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uk

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Hi rsp blake I wasn’t aware century are doing an extended tail boom and I am sure that I wont be looking at it either, the one I am using is excellent and just view this modification as a quality upgrade the conversion is being tested at moment and its all looking good I am using some components of heli leisure’s and I like the quality of the parts I like the predator but when I had problems I, e- mailed century USA many times but did not get a reply which I was very disappointed with so I am not bothered any more I can solve it my self and have been sharing my modifications with you all so happy flying chaps cheer’s Steve.

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10-16-2005 12:49 AM  13 years agoPost 9
hayabusa

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uk

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Hi I have test flown wren/predator which can now take up to 830mm blades its got a 25mm boom with servo fitted on tail boom and I am using my modified predator tail rotor box it flew without a hitch and I cant wait for my 800mm blades to arrive I am going to strip the tail and check it before I do any more flights to see how the conversion has held up and make sure there are not any problems cheer's Steve.

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10-22-2005 09:14 PM  13 years agoPost 10
rspblake

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London uk. coulsdon

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Steve hi

Can you send me pictures?

I do remember reading about a boom extenstion using the same drive with a lock in section to the ends of the boom to make longer.

Think on a Gasser dont think it was a pred.

Is that how you made yours or was it a new boom and TT drive?

Carbon or Ali boom?

But the century 800mm upgrade is for the gasser condor I think.

Rob
.

(gunnell_s) still owes me money! ... web evorc.com

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10-23-2005 11:27 AM  13 years agoPost 11
NEIL2-UK

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UK - South East

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Blade Sizes for turbine weight, etc...
Hi Rob (and Hayabusa)

I'm looking to see if Century upgrade (designed for Condor I believe) is available/suitable. But the 25mm boom conversion is designed to deal with the issue of 'boom flex' on a long and skinny Predator boom if it was extended to take the 800+ length blades.

In standard form the Predator is set for 720mm blades... and as Hayabusa has pointed out is a bit marginal for flying in some circumstances with increased weight of turbine.

The Raptor takes only 710mm blades, and with 105mm NHP tails is marginal. This is the prefered option out of all the various tails tested... and I think Hayabusa will concurr on that.
Bearing in mind the weight of turbine upgrade, the heli is working well on 120 CCPM, but I think that a longer boom kit is really an ideal option to improve the flight envelope.

RotorTech blades have worked well on the Predator, at 720mm, but they have a lot of weight and have inertia for good autos... but other blades that you might use if you want response for more extreme flying are lighter and suffer a bit with autos and the weight of the turbine on such a small blade disc.

I've come up with another blade option that Hayabusa will be flying over the next month (subject to weather)... which you have seen on Dean J's 3D TT-Cuatro and has been tested to extreme since March.

Thanks
Neil

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10-23-2005 05:32 PM  13 years agoPost 12
coolice

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Northamptonshire, England

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Hey,

Yeah, I have had this conversation with Hayabusa going back well over a month ago now, regarding blade length on the Predator turbine and more recently with Bell Bloke.

From my own experiences the stock setup is very capable, still more so than I have pushed it if I am honest. But the smaller rotor disk, flying a relatively heavy turbine airframe does suffer in some manouvers.
Something I have mentioned elsewhere to if I recall.

The first one that springs to mind is obviously the auto performance, or lack of reserve at the end to cushion the landing. It can be done safely but you have to use more negative than normal to wind the blades up on the way down.

Another manouver I have tried that I feel will benefit from a bigger disk is tail-in inverted funnels. So far my attempts have seen the models nose tuck back out of the inverted, with the turbines weight taking over. I think also I have not entered the manouver as quick as I need to be and the wind was blowing a gale on the day, so I am awaiting another day to give it a go some more.
A plus point with going to a longer boom will be that the CG of the model will hopefully come back closer to the main shaft, making the model fell better inflight.

Having seen Bob Johnstons Cuatro flying on 810mm blades gives you a clue that this is the route to go down, to bring the heavier turbines performance more inline with a 90.

The longer boom from Century is as stated above, derived from the Condor and is available from CenturyUK or any Century stockists for that matter. Along with the longer stainless steel tail drive to go with it.
Also, the boom wall thickness has been increased to add more rigitity and reduce the flexing in the boom. Which is more important the longer we make the booms.

I've also got some solid head dampers to try at some stage from my buddy John Parker. Over time with the model and the hard I have pushed it, I have come to see that head dampers do not last long with extreme flight and I go through a set every few months with constant use through the show season.
Another point brought to my attention by John, after seeing me fly the model, was that in extreme flight if you pull up hard on the elevator there is a risk, more so if your dampers are to loose, that the disk will deflect with the command but the fuselage being heavier will take longer to react. Hence the main rotors may come into contact with the boom or tail blades if their long enough.
With a nice set of blades and the harder dampers it may prove to be a good combination.

I am yet to decide what blades to go for as yet.
The 800mm Rotor Techs are nice but expensive, but do have a nice lifting section I have heard which is good for commercial lifting applications.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-23-2005 09:46 PM  13 years agoPost 13
Bell Bloke

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UK

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I'm trying SABs 810s £120. Lovely!

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10-24-2005 10:28 AM  13 years agoPost 14
NEIL2-UK

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UK - South East

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Blades Depend on flying style...
Ian, Hayabusa and Rob... and anyone else

Noted your comments in line with what Hayabusa and myself and some others have been working on for some while...

The Rotor Techs are nice (If you talk of price you should look at some others more pricey!)... but possibly too heavy for 3D response.
The Condor boom may be OK, but it would also depend if the tail box has been improved suitably for these later conversions... especially the bearings. For the longer tail drive I use my own Stainless tube supply or Carbon tube from a supplier in Germany, and upgrade the bearings in the drive supports.

There are different stiffness damper rubbers available from Century Distributors who deal with Predator... and I use the stiffer ones with my Predator Turbine conversion. Like all helis there are a number of options to do to make changes to suit your own flying style. The first thing though is to improve reliability of basic airframe.

Ref mention of John Parker. When he was flying Predator I understand his tail problems were solved by Bergen parts... which goes back to the common link of Bergen/Century about 6 years ago and the option of upgrades that fit... but a bit pricey.

Bell Bloke... what boom conversion are you using for your longer blades?

NEIL

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10-24-2005 10:53 AM  13 years agoPost 15
Bell Bloke

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UK

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A Century jobby, it should be here soon, I hope.

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10-24-2005 11:03 AM  13 years agoPost 16
coolice

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Northamptonshire, England

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Hey All,

Oh yeah I totally agree on main blades, blade choice is very much influenced by flying style. Thats why I am always interested to see what one's Bobs flying and also what other 3D guys are using.
As we've mentioned, due to there being a weight penalty a make of blade we feel flys well on the 90's may not suit our machines now.

I must admit to really liking the Rotor Techs, as has been said already the auto-rotation performance is excellent (stretched me a few F3C autos when I've needed it ).

Century do now have a more beefy tail gear box moulding, I have these casings on my F3C Predators and although I cannot tell any realy difference in their flight performance, they are stiffer.
Bearings, I've not really had much trouble with. I noticed more the slight under size in the tail output shaft more and changed that as a personal thing when I bent the originals.

Dampers again, Century have a good assortment to suit the Predator. The best so far for me are the harder 90 durometer (I think) one's that came in a set of four "O" ring shape dampers. The user then assembles the head up with two damper rings each side.
These dampers are lasting the longest with me, as where as the softer black donut ones and harder red versions didn't fair to well.

You are spot on with John, he is still at present flying a Bergen tail assembly, it suit's his style of flying very well with the extra stiffness and tail throw. But he will soon be changing, while he doens't have a problem with this current setup, sourcing parts when the worst does happen is time consuming.
Also Century, with their better booms now and soon to be seen metal tail gearbox, will have everything he needs to be sorted all by Century.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-24-2005 12:34 PM  13 years agoPost 17
NEIL2-UK

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UK - South East

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Boom Fittings...
Ian

The longer boom kits with thicker tube material is still of same outer diameter... which is a bit slack in boom clamp.
With a thicker material you have a smaller bore to slide the bearing holders into... and the 'O'rings on the outside of the bearing holder need to be changed as they are too tight a fit (along with fitting better quality bearings). I note Century service in US have also now realised this!

The output shaft on the tail gearbox is a bit 'hit and miss' for correct diameter... I use, and recommend, a Raptor shaft as it is a better fit and less likely to bend (which you have already experienced with standard shaft), and also use two set screws (grub screws) to hold components in place on shafts.

The Century upgrade of 'speed up' gears for the tail box is also a useful option to give good tail authority, if you are not using high head speeds... and again I would recommend to replace bearings with good Japanese or German bearings as a more reliable option.

The new thicker plastic tail casings are an improvement... except that you have to be more careful that bad tollerences on gear mesh setup does not side load bearings too much.
Metal casings... sometime next year maybe, so I'm told by Century UK.

Just a few of my findings above...

NEIL
HeliLeisure TurbineTechnics ...for a better solution.

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10-24-2005 02:10 PM  13 years agoPost 18
coolice

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Northamptonshire, England

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Neil,

I must admit to never having had a problem with the boom diameter in the clamping end at the back of the frames. The place I have experienced it over time, as oil and grime get in places it shouldn't, is out the back on the tail rotor assembly.
Also the plastic locating lugs in the gearbox casings get eaten way by the slightly harder boom.

Quick fixes for this is to add a small self tapper, but this we all know from previous experiences.
The new tail casings do provide a better clamping action onto the boom and so help much more compared to the previous setup. However it may still be advantagous to keep an eye on the clamping, but this comes down to routine check's with hard flying anyway. The harder the machine is flown the more there is to watch for.

Tail rotor shafts have come out under sized in a few batches, which is a shame but are not easily bent in flight. Mine got tweeked landing my 90 on it's head button at Charmouth last April
What I use is a QuickUK Raptor 50 head spindle (nice price), cut to length and with flats ground on to suit. I find it a very nice fit within the I/D of the bearings and hence tightens the tail up nicely.

The use of two grub screws is very important as you say, with two holes drilled & tapped in the gears I am sure most if not everyone fits two even during building, even if they have to get one from another place as it's not in the kit.
This is basic stuff really to promote better reliability, although not mentioned in the manual. However the model isn't really aimed at the beginner anyway.

The speed up gears are a good idea, however I've never felt the need to use them in any of my machines, finding that the tail with a GY601 holds very well already.
The Turbine running a 401 / 9254 also locks in well, all using stock RT's tail blades.

Century metal tail setups, I cannot be more specific as to release dates etc. as I have only just seen pictures and got very excited in the process.

As is the Predator tail rotor is solid, a good metal pitch slider unit we lack at present, but I know your company markets one which looks good and fills that void should someone desire one.

Although not needed, metal components like the tail gear box, pitch slider etc. just look good on any model. It is known a metal tail slider will wear less than the stock item, but isn't a necassity.
Pete Roper use's a stock tail setup on his Pred and gives it serious stick with no failures.
.

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters

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10-24-2005 03:01 PM  13 years agoPost 19
MikeDD

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Elkhart, IN

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The Condor in the video from the IHobbyExpo looks to have an open metal tail gearbox.

Michiana R/C Choppers

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10-24-2005 05:55 PM  13 years agoPost 20
NEIL2-UK

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UK - South East

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Predator Parts...
Ian

Experience is that plastic tail pitch slider tends to pull apart... same unit from myself is used on Raven/Falcon also.

You mention the 9254... and I had an interesting conversation with Colin McG during Friday afternoon on this (and the Pred tailbox). Give him a ring on the 9254 as his comment concurr with others that I've heard.

The tail boom diameter is a fraction undersize on metric sizes... and I guess the US is a bit down on this being still based on imperial sizes, and so dimensions get a bit mixed up!
I use loctite of a non-permanent grade (such as low strength stud lock) when fitting the boom to frame clamps and when fitting tailbox to boom... and it has made a big difference.

Re: Grub Screws, and the model being for more experienced builders. There should still be two available to fit.

GUESS WHAT... yes I like the Predator, but it needs some work on some of the components to make the airframe more robust/reliable for turbine use (and even Gasser and 90 size also)... but with all the changes and upgrades I make on my Predator Turbine it adds to the cost.

If You look at how the top 3D flyers fly and what blades they use (Your ref to Bob J)... you may well be surprised at what is used on Dean Jackson's TT-Cuatro... with a video on the website shortly once I've finished commissioning a new computer.

Whilst talking of blades... what about FLYBAR setup and paddles! Dean's TT-Cuatro for 3D is a real hi-tec development (especially when I see some of the products and their costs).

- OK here it is... Standard Cuatro flybar cradle setup (no need to change bearings as Robbe are high quality and I always use hi-spec German or Jap anyway), Raptor 60/90 flybar, AND Predator 'grey' paddles with tapered tip cut off (and you will know that the grey paddles are the lighter Predator ones).

I'll let you know the blades that have been flown, since March, when I give out some of the 3D spec with the video on the website.

More information on the extreme 3D developments as they are also tried by others and fully tested (Note to Chopper Jockey... fully tested! Thanks for your lame comment)

NEIL

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